Anatomy muscle pretest

When an organism dies, its muscles remain in a contracted state termed "rigor mortis" for a brief period of time. Which of the following most directly contributes to this phenomenon? There is no

ATP to break bonds between the thick and thin filaments.

The contractile unit of muscle is the

. sarcomere.

Which of the following is the correct sequence that occurs during the excitation and contraction of a muscle cell? 1. Tropomyosin shifts and unblocks the cross-bridge binding sites. 2. Calcium is released and binds to the troponin complex. 3. Transverse tubules depolarize the sarcoplasmic reticulum. 4. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP. 5. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.

5, 3, 2, 1, 4

In order to initiate a skeletal muscle contraction,

a neurotransmitter must first be released.

Duchenne muscular dystrophy is a sex-linked condition in humans that results from abnormal dystrophin protein. The condition results in progressive weakening and atrophy of muscles, usually beginning with the legs. This is most consistent with which of the following?

a structural abnormality of the sarcomere

What is the role of calcium in muscle contractions?

bind to the troponin complex, which leads to the exposure of the myosin-binding sites

During the contraction of a vertebrate skeletal muscle fiber, calcium ions

bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed.

transfers energy to ATP in muscles

creatine phosphate

A backup energy source for muscle contraction is

creatine phosphate.

When a sufficient (threshold) stimulus is applied to a muscle cell, the muscle cell will

experience a short lag (latent) period.

Which of the following could you find in the lumen of a transverse tubule?

extracellular fluid

supplies muscle cells with glucose

glycogen

A muscle contusion can occur if one

has a brick fall on the muscle.

When a person performs strength enhancing exercises, the skeletal muscles get larger as a result of

hypertrophy.

All of the following factors can cause skeletal muscle atrophy except

increased neural stimulation to the muscle.

The lifting of a weight is an example of a(n) _____ contraction.

isotonic

Muscle originates from

mesoderm.

Muscle cells are stimulated by neurotransmitters released from the synaptic terminal of

motor neuron axons.

Which function associated with muscle would be most directly affected by low levels of calcium?

muscle contraction

Which are stronger muscles that are adapted for moving heavy loads over short distances?

muscles that have pinnate arrangement of their fibers like the gastrocnemius

oxygen storage for some muscle cells

myoglobin

Which of the following does not form part of the thin filaments of a muscle cell?

myosin

A muscle condition whereby there is bone deposited in muscle is

myositis ossificans.

weaker contractions

nonstriated muscle cells

The _____ is the attachment of a muscle to the least mobile point.

origin

What kind of muscle controls peristalsis?

skeletal

sacromeres found in

skeletal and smooth

What structural feature(s) contribute(s) most to the diverse adaptations for animal movement?

skeletal system and muscular system

stronger contractions

striated muscle cells

A sustained muscle contraction due to a lack of relaxation between successive stimuli is called

tetanus.

Skeletal fibers may be classified as either oxidative or glycolytic. Which of the following muscles would be called glycolytic?

the ones most easily fatigued

Which of the following are shared by skeletal, cardiac, and smooth muscle?

thick and thin filaments

What happens in the sarcoplasmic reticulum as a result of the chemical changes that result from the arrival of acetylcholine at the sarcolemma?

Calcium ions are released.This

When ATP is deficient and calcium is not pumped back into the sarcoplasmic reticulum, _____ will occur.

a. rigor mortis

The neurotransmitter for skeletal muscle is

acetycholine.